Investigation of preparation conditions and fouling properties of polyaniline membranes with improved electrical conductivity

In this study, the poly(2-acrylamido-2-methyl-1-propanesulfonic acid) (PAMPSA) doped polyaniline (PANI) structure was synthesised using the oxidative polymerisation method and graphene (Gr) modified composite membranes with improved electrical conductivity were then prepared using the synthesised PANI structure. The prepared membranes were characterised structurally and morphologically, their performance and fouling properties were investigated and electrical cleaning studies were carried out to evaluate the effectiveness of electrical conductivity improvement in cleaning. XRD analyses confirmed that Gr was modified into the membrane structure. Cross-sectional SEM image examination showed that all composite membranes were sponge like structure and the top dense layer became more porous but thicker with Gr doping. Conductivity measurements revealed that the electrical conductivity of the membrane structure increased with Gr doping and the membrane doped with 5% Gr had a conductivity of 2.16x10-3 S/cm, which was 4.2 times higher than the membrane without Gr modification. In the rejection studies, it was observed that all membranes exhibited rejection performance above 90% for BSA and above 80% for HA. As a result of fouling and simple hydraulic cleaning studies, it was determined that the total fouling rates for BSA increased with Gr modification and increasing Gr ratio and the fouling rate increased from 75% in the membrane without additive to 77.6% in the membrane with 5% Gr modified and the fouling was highly irreversible. HA fouling resulted in relatively lower fouling and higher reversibility. The electrical cleaning studies showed that electrical cleaning provided higher reversible fouling and flux recovery rates for both unmodified and 5% Gr modified membranes compared to simple hydraulic cleaning, and the reversible fouling rate for BSA was increased from 5.8% to 39.7% and the flux recovery ratio was increased from 28.2% to 61.9% for 5% Gr doped membrane. With the results of the study, it was confirmed that the improvement of electrical conductivity with Gr additive increases the electrical cleaning efficiency of the membranes.